I have an opportunity to buy a link on a PR8 website, but it is not related to my site. I wonder if it wouldn't be better if I created a simple blog with unique content that would be related to my site and would link from this blog to my site, and then I would link from the PR8 site to my blog. After the next PR update my blog could get e.g. PR6 and this way I would get a PR6 related link for my site. I think this would be better than a PR8 non-related link. Or should I rather link from the PR8 site directly to my site even if it is not related?
I would go directly, that buffer is going to kill quite a bit and content is just one of many factors even though it has more and more relevance these days.
Are you kidding? Sure contextual relevance is a factor but there are many factors and its just one...
when you are talking about PR, it doesnt matter the site is related or not, the related affect much on the SERP but not the PR You still get the same PR juice no matter what is your niche
Niche is important when it comes to trying to drive traffic. But Google does not pay attention to the niche of high ranking websites. For example, you could own a website that sells farm equipment but it would be cool if you could get a backlink from ESPN, a high ranking website.
The Google Panda update focused entirely on the content and its quality, that is why directory submissions found themselves pretty much useless. Also I think that it would be better to have a relatively lower PR link from a related website as compared to a high PR site with no relevance.